Single use cameras are commonly sold preloaded with a cartridge of film. In order to reduce complexity and costs, a rewind mechanism is omitted from the camera. Instead, the film is prewound and during use is advanced back into the film canister. A number of approaches have been followed in loading and prewinding film cartridges for single use cameras. In some approaches, such as one taught in U.S. Pat. No. 4,972,649; film is prewound into a roll outside the camera body and then loaded. A shortcoming of these approaches is that the film roll must be handled after it is formed. This presents a risk of film damage and may add complexity to necessary equipment. In some other approaches, also taught in U.S. Pat. No. 4,972,649; the cartridge is loaded, the camera is light-tightly closed, and the film is then prewound. In still other approaches, such as taught by U.S. Pat. No. 5,311,231; the cartridge is loaded and then the rear opening of the camera body is closed and the film is prewound through a bottom opening, which is later sealed. The latter two approaches have the shortcoming that film guiding is provided primarily by the camera body, rather than loading apparatus. This places constraints on the camera body in terms of required tolerances and the like and may, in addition, slow throughput speeds. Still another approach is taught by Japanese Kokai 6-295022, European Patent Application No. 0743546-A, and Japanese Kokai 8-171180. In this approach, the film is wound onto a second spool, rather than being wound into a film roll. The back of the camera is not mandatory for guiding the film, since the second spool tends to restrain the film.
A number of separate procedures have to be performed to load a film cartridge into an incomplete camera and prewind the filmstrip. Bi-directional and unidirectional motion can be provided to various parts by separating procedure steps and necessary tooling. On the other hand, it is desirable to integrate procedural steps and necessary tooling to minimized wasted motion and reduce costs.
It would thus be desirable to provide cartridge loading apparatus and methods which allow both bidirectional filmstrip motion and unidirectional thumbwheel motion within a camera frame assembly.